Engineers are trying to figure out how to get a stream back into its banks before it does damage to nearby homes.
Town Engineer Fred Boone presented Knightdale council members with a trio of solutions at a meeting last week, to keep the unnamed stream from continuing to move.
The stream empties into Mingo Creek and engineers have pointed to upstream development as the cause of increased sediment in the creek, which has caused the water to seek an easier path downhill toward Mingo Creek.
That means some homes in the Parkside Commons neighborhood have seen their back yards washing away at an alarming rate. In one case, the stream ditch now comes within six feet of the foundation of a home’s back deck.
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Boone said the upstream development has created runoff that deposits sediment in the stream further downstream. But he says much of that upstream development was built before stricter stormwater regulations were in place.
The town hired an outside engineering firm to look at the problem and offer suggestions. Boone said the state has also looked at the problem and recommended the town embark on a full-scale mitigtion project to repair the damaged stream and prevent future problems. The engineering firm offered other solutions, but Boone cautioned council members that the work was going to be difficult.
“This project is a long-term project. It’s going to be an expensive project. It is a real problem and one with no easy solution,” Boone said.
The engineering firm, McAdams Engineering proposed three solutions: leaving the stream bed in its new location, but shoring up the banks to prevent future erosion; raising the stream bed to connect it with a larger flood plain, allowing water to spread out more without causing damage; and relocating the stream to its original location and stabilizing the creek banks to protect against further erosion.
Those solutions will cost the town anywere from $31,500 to $78,700.
Boone is currently working with bidder to reduce the costs if the town were to pursue the third option, which is estimated to cost $55,000.
“We can’t do much with the original drainage easement, because it’s really a creek-wide issue,” Boone said.